The hydraulic brake system used for a bicycle may be seemed to one of the most popular hydraulic devices. It is mainly that a brake master cylinder driven by a handle is arranged at the handlebar and then connected to a brake caliper through a hydraulic line. When the handlebar is pressed by a rider, the piston inside the master cylinder is driven to move forwardly by the handle, and then the oil inside the master cylinder is pushed to the slave cylinder of the caliper. Then, the brake pads are moving toward the brake disc and further the wheel starts to be braked.
However, the brake master cylinder must be arranged adjacent to the handlebar and hard to be adjusted. And it is inconvenient that the two holes with 0.5 mm diameter may not be adjusted after finishing assembly.